The present invention relates to machines for converting sheet stock material into a dunnage product and, more particularly, to a method and stock material supply which greatly facilitates splicing of a succeeding supply of stock material to an almost spent supply of stock material.
Cushioning conversion machines convert sheet stock material from a supply thereof into a cushioning dunnage product. The sheet stock material is usually supplied in the form of a roll from which the sheet stock material is payed off for conversion by the machine into the dunnage product. When the roll is spent, a new roll is loaded in place of the spent rolland the leading end of the new roll is inserted into the machine. One way of accomplishing this is to splice the leading end of the new roll to the trailing end of an almost spent roll. When the machine is once again operated, the trailing end of the almost spent roll will pull the leading end of the new roll through the machine.
Two techniques heretofore have been used to splice a succeeding supply of stock material to an almost spent supply of stock material. One way was to use several strips of tape to attach a leading end of the succeeding supply of stock material to a trailing end of the almost spent supply of stock material. To facilitate splicing, some conversion machines were provided with a splicing plate on which the trailing end is held while the leading end is spliced thereto. Another way by which splicing has been accomplished was by spraying a liquid adhesive on the trailing end of the almost spent supply and then pressing the leading end of the succeeding supply to the adhesive covered trailing end. The adhesive functions to bond the trailing end and leading end together.
While the above methods of splicing have proven to be feasible, they are not without drawbacks. For example, if the almost spent and succeeding supplies of stock material are to be spliced by taping then the machine operator must have a supply of adhesive tape handy. Otherwise, delays in productivity may ensue. Also, the prior art taping process was somewhat tedious, particularly when multi-ply stock rolls were used as normally was the case. Additionally, if incorrectly applied, the tape may become dislodged and jam the machine or otherwise affect the converting of the stock material.
In regard to the spray adhesive, the adhesive may be oversprayed on the stock material or on parts within or in close proximity to the conversion machine. If the adhesive is sprayed on unintended areas of the stock material then the stock material may jam the conversion machine or otherwise deleteriously affect the quality of the dunnage product. Overspray on parts of the machine may affect the operation of those parts, in particular, if the parts require movement.
The inventor of the present invention appreciated a need for a supply of stock material and a means for splicing the same which would solve the above problems.
The present invention provides an improved splicing method and supply of sheet stock material which simplifies splicing a succeeding supply of stock material to an almost spent supply of stock material. According to the present invention, a supply of sheet stock material includes at least one ply of sheet stock material rolled or folded into a compact configuration, such as a roll of wound material or a stack of fan-folded material. The ply of stock material has disposed on a leading or trailing end thereof, a pressure sensitive adhesive layer and a removable release liner covering the pressure sensitive adhesive layer.
According to an aspect of the invention, there is provided a method of converting sheet stock material into a cushioning dunnage product, comprising the steps of operating a cushioning conversion machine to produce one or more dunnage pads from a supply of sheet stock material until the supply of sheet stock material is almost spent, removing a release liner to expose a pressure sensitive adhesive layer on a leading end of a succeeding supply of sheet stock material or on the trailing end of the almost spent supply of stock material, applying the leading end of the succeeding supply of stock material to the trailing end of the almost spent supply of stock material such that the pressure sensitive adhesive layer bonds the ends together, and operating the cushioning conversion machine to produce one or more additional pads.
In an embodiment of the invention, the step of removing the release liner includes removing the leading end of the succeeding supply of stock material and the pressure sensitive adhesive thereon from an adjacent layer of the succeeding supply of stock material or removing the trailing end of the almost spent supply of stock material and the pressure sensitive adhesive thereon from an adjacent layer of the almost spent supply of stock material. The step of removing the release liner may include removing a paper strip release liner from the leading end of the succeeding supply of stock material or from the trailing end of the almost spent supply of stock material.
In an embodiment of the invention, the leading end of the succeeding supply of stock material is placed over the trailing end of the almost spent supply of stock material. Alternatively, the trailing end of the almost spent supply of stock material may be placed over the leading end of the succeeding supply of stock material. In the case of a multi ply stock material, the step of removing the release liner and the step of applying the leading end to the trailing end is repeated for each ply.
According to another aspect of the invention, there is provided a supply of sheet stock material for use in a cushioning conversion machine. The supply of stock material includes at least one ply of sheet stock material rolled or folded into a compact configuration. The ply of sheet stock material has on a leading or trailing end thereof a pressure sensitive adhesive layer and a removable release liner covering the pressure sensitive adhesive layer.
In a preferred embodiment of the invention, the removable release liner comprises an adjacent layer of the sheet stock material. The adjacent portion may include on its surface facing the adhesive layer a surface treatment for permitting removal of the adhesive layer from the adjacent portion. The pressure sensitive adhesive layer and the release liner may extend substantially across the width of the ply of sheet stock material, although the adhesive layer and liner may be narrower in width than the stock material to provide tolerance in applying the adhesive layer.
In an embodiment of the invention, the pressure sensitive adhesive layer may form a plurality of adhesive layer portions. The adhesive layer portions may, for example, be transversely spaced across the width of the ply of sheet stock material to form a discontinuous strip of adhesive that extends across the width of the sheet stock material. A single release liner may be provided to cover the multiple adhesive layer portions so that, when released, it exposes all of the adhesive layer portions simultaneously. Alternatively, multiple release liners may be used to cover the respective multiple adhesive layer portions, in which case the release liners are independently released.
The pressure sensitive adhesive layer may be disposed on the outer or inner surface of the leading or trailing end of the ply of sheet stock material. In a preferred embodiment of the invention, multiple plies of stock material each have a pressure sensitive adhesive layer on a leading or trailing end thereof and respective release liners covering the same. The trailing or leading edges of the plies of sheet stock material may be coterminous or longitudinally offset from one another. The trailing or leading edges of the pressure sensitive adhesive layer may also, or alternatively be longitudinally offset from one another. In an embodiment, the trailing or leading edges of the pressure sensitive adhesive layer may be longitudinally offset from trailing or leading edges of the plies.
In an embodiment of the invention, the pressure sensitive adhesive layer forms a strip. The strip is attached to the ply on a leading or trailing end thereof. The strip enables the pressure sensitive adhesive layer feature to be retrofitted with an existing supply of stock material.
In an embodiment of the invention, the pressure sensitive adhesive layer comprises a reduced strength adhesive, enabling a release liner to be cleanly and easily removed from the adhesive layer to expose the adhesive layer, which exposed adhesive layer can then be removably adhered to the sheet stock material. Also, the adhesive layer may include separate adhesive layer portions including, for example, a permanent bond type adhesive layer where it is desired to keep the adhesive layer intact once spliced, and a reduced strength adhesive layer where it is desired to be able to easily remove and/or reposition the stock material.